In late 1970s, the aluminum alloy windows and doors and curtain-wall industry started in China. The aluminum alloy glass curtain-wall was promoted and applied in the construction industry, and the aluminum alloy windows and doors and curtain-wall industry was developed quickly from nothing, from imitation to self-development, from undertaking construction of small projects to big ones, from production of low-end products to high-tech products, from construction of glass curtain-wall used for doors and windows of low-rise buildings to high-rise buildings, from processing simple low and medium-grade profiles to high grade profile with extruded section, and from relying on imported products to undertaking projects overseas. In 1990s, the emergence of new construction materials further promoted the development of the construction curtain-wall; a new type of construction curtain-wall, namely the metallic curtain-wall, appeared one after another all over China. The metallic curtain-wall means a curtain-wall with the front panel of the curtain-wall being metallic plate, which is a new type of construction curtain-wall, with the glass of the glass curtain-wall replaced with metallic plate. The major materials of the metallic plate include the flowing: aluminum compound plates, single-layered aluminum plates, aluminum cellular boards, fire-proof plates, titanium-zinc-plastic-aluminum composite boards, sandwiched insulation boards, stainless steel plates, color-coated steel plates, enamel steel plates, and so on. The curtain-walls are different because of different materials of the front panels. Therefore, different processing methods should be carried out in the construction process. Because of the excellent processing performance of metallic sheets, various color and good safety performance, the metallic curtain-wall is fully suitable for different kinds of complex shapes, and any concave and convex shapes, or different types of curved lines can be added. As a result, architects can make many different designs, and therefore the metallic curtain-walls are very popular and developed quickly.
The relevant patents disclosed abroad are as follows:
    1. Three-dimensional stamping full-length welding polished aluminum curtain-wall. [1] The three-dimensional stamping full-length welding polishing is the method of producing ship model or airplane. In this technology, the curtain-wall is made by splicing the small stamped aluminum plate blocks of 6 mm in thickness. In the research, aluminum plate of 6 mm in thickness is used, and it is made into a continuous shaped surface by means of welding (argon arc welding, full-length welding treatment), followed by polishing to hide seams, so as to gradually form the three-dimensional housing. Finally, marine paint or gel coat is coated on the surface for beautiful appearance and anticorrosion. Every piece of the aluminum plate needs customized manufacturing. Therefore, manpower and machines are necessary, and the full-length welding and polishing of the plates require massive consumption of manpower. The whole technical process requires much time and efforts and the cost is very high.    2. Three-dimensional tension anchoring type metallic curtain-wall. [2] The curtain-wall is made of stainless steel plate, with a customized steel structure. Because this method needs to be separately processed to form the customized steel structure, the products are high in prices. The waterproof treatment needs to be carried out on both sides. Because it is difficult to form waterproof layers, it is necessary to use double skin facade. The major structural components are formed by customized processing to improve the surface precision; however, this greatly increases the costs. In this technology, every separate component is subjected to customized cutting, and there is much waste generated. During the construction process, a big team is required from processing to installation.
Thus, the personnel cost is increased. The problems of this process include big construction errors, small curvature, and bad arcing. In addition, it is necessary to form an inner waterproof layer. However, many rivet heads are exposed to the outside, which impacts the appearance and makes it difficult to remove dusts collected thereon.    3. Three-dimensional stamping type metallic curtain-wall. [3] The curtain-wall is made of stainless steel plate with customized double curved surface made by means of folding and stamping. The curve is formed by a layered system of a secondary structure. That is, it is necessary to cut the steel structure into multiple sections and then connect the sections together to form the curve. It is complicated to attach another layer on the precise frame. Because it is difficult to manufacture waterproof layer on the surface layer, it is necessary to carry out waterproof treatment on both sides. The technology is relatively imprecise, and it requires much manpower and much cost. Components of the steel structure are standard and precise. The key point of changes is to control the length of each section of the steel ribs and each step of the customized manufacturing. This system requires high precision and is difficult to construct. In addition, it requires construction of inner waterproof layers, which cost time and manpower.
In sum, because the digital parametric design has become a new trend in the construction, the inner and outer metallic curtain wall is random and abstract in shaping, and the double-curve shaping is not the traditional bending or bent arc which is difficult to be solved by geometric cutting. Even if it is realized constrainedly, the cost is too high; the product quality is difficult to control because of the processing precision, construction difficulty and even non-uniform stress distribution and insufficient stamping force of metallic material. Therefore, it is necessary to develop a metallic curtain-wall that is low in price, easy in construction, convenient in maintenance and even in stress distribution.
Reference:
    [1] Semi-monocoque aluminum construction    CASE STUDY, Lord's Media Centre, London.1999    Design: Future Systems Architects.    Fabrication: Pendenis Shipyards.    [2] 3D Custom Panel System.    CASE STUDY, Experience Music Project, Seattle.2000    Design: Gehry Partners LLP.    Construction: Hoffman Corp.    [3] 3D Standard Panel System    Experience Disney Music Hall, Los Anglese.2003    Design: Gehry Partners LLP.    Construction: Hoffman Corp.